For example, a JPEG file image, which is photographed and compressed by a digital camera or the like, is reconstructed by a personal computer (PC) or the like and is displayed, is printed via a PC printer or a direct printer, or is printed by a print shop. At this time, if photographed image data has high image quality, it need only be faithfully reconstructed, and is displayed or printed, thus posing no problem.
However, some photographed image data suffer color fog, insufficient contrast, inappropriate exposure, and the like, and must undergo image correction to obtain a high-quality print result. Especially, in case of a portrait image, if that image is reconstructed and printed to have an appropriate face color, such photo leaves a favorable impression on a person who sees that photo, and photo quality can be improved. Even when a landscape or an object is photographed, an image is preferably reconstructed and printed to have an appropriate color of a target photographed object.
For example, in case of a silver halide photo, an exposure amount upon printing is preferably changed for each original image so as to obtain a high-quality photo. In order to determine the exposure amount upon printing, if a person appears in a photo, it is convenient to focus on the face color. Since it is known that the face color is a flesh (or skin) color, it is possible to determine the exposure amount so that the face color of the person who appears in the printed photo matches the flesh color.
As conventional methods for recognizing an image from an image file of digital camera, for example, “Japanese Patent Laid-Open No. 8-161497”, “Japanese Patent Laid-Open No. 2000-48036”, “Japanese Patent Laid-Open No. 11-238067”, and the like are known.
These methods detect a similarity or coincidence level with a designated image. In case of “Japanese Patent Laid-Open No. 8-161497”, a coarse coincidence level is obtained for each block of the DC component. After that, a candidate image region undergoes a reconstruction process to obtain a fine coincidence level as non-compressed data.
In case of, “Japanese Patent Laid-Open No. 2000-48036”, there is disclosed an image processing apparatus which inputs or generates search data, and determines similarities between this data and a plurality of image data. Furthermore, in case of “Japanese Patent Laid-Open No. 11-238067”, a query image undergoes wavelet transformation to generate a compressed image. Also, a designated image undergoes wavelet transformation to compare respective feature data, thus determining a similarity.
On the other hand, as a method of correcting an image, upon printing an image photographed by a digital camera, an application or that of a printer driver analyzes photographed data using a histogram or the like, and uniformly applies image correction such as contrast correction, white balance correction, exposure correction, and sharpness correction, and the like.
However, it is impossible for the conventional method to accurately find out an image of interest to be corrected, and to correct that image of interest to a desired color.
More specifically, when, for example, a JPEG file image photographed by a digital camera or the like is reconstructed and displayed or printed, a method of finding out an image of interest such as a person or the like from the JPEG file image to be able to correct the image of interest so that the image of interest is displayed or printed more satisfactorily like in a print process of silver halide photos must be determined.
On the other hand, a method that can attain a detection process with the possible lightest load is demanded so that a device which has low data processing performance such as a direct printer which directly prints data from a digital camera and the like can use it.